To provide a method of flame treatment of a surface, which can improve the adhesion of ink to the surface of a molded article of a cycloolefin resin, prevent the occurrence of a solvent crack, and prevent the occurrence of a crack during the long-term storage of the molded article, and a molded article manufactured by the method.

In the method of flame treatment, the ratio of the inner flame distance L to the inside diameter D of a burner nozzle, L/D, is (80 to 170):1, and the velocity of the outside surface of the molded article to be treated is 50-100 cm/s when the outside surface passes the front of a gas burner.